1) Yes, mostly because it's bad for google's business
2) Also, are google then responsible for the content released on those apps? It could be an infinitely deep layer of contracts etc. At least with DLC there is only one extra layer of crap, much easier to control.

"PLEASE NOTE: This app lets you purchase digital content using actual money. You can configure parental controls for in-app purchases, which will require your Amazon account password or a 4-digit PIN, by going to the Settings menu from within the Amazon Appstore."
Screw that.